The "detailed requirements" part is an outright spoiler tho. It totally strips the problem out of the problem, and all what is left is typing in a bunch of characters. I think it goes too far.

One issue I see is that negative inputs can be surprising: they are not mentioned in description, and solutions which just implement the triangle inequality theorem can get them wrong. IIRC, some languages also have inputs which trigger overflow. At the very least, ranges of inputs should be specified. Otherwise it's just getting surprised on every ATTEMPT with some new type of input.

severely?

• hey, check out these 3 numbers
• can they form a triangle?

... why?

Can you share what parts exactly you find not clear? I am willing to rewrite the kata as much as necessary, but I need to know what exactly are the problems with it.

I would recommend re-writing this Kata as it severely lacks any sort of clarity in the way it was written.